Advances in satellite terminals improve their reliability

Oct 06, 2011

As very-small-aperture terminals emerge as a major component of the Defense Department's plans to upgrade military networks, varying requirements are altering the focus of teams designing future products.

As equipment suppliers strive to reduce size and improve ease of use for warfighters on the tactical edge, the logistics personnel who keep these troops supplied are also making use of VSATs, extending the development focus from size to reliability.

Equipment designers are pressing forward on two paths. One focuses on lighter, easier-to-use gear that’s carried into the field. The other aims to improve reliability for stationary operations, such as supply chain management. These users must often move rapidly to follow troops.

The drive for improved communications support for logistics began during Operation Iraqi Freedom in 2003. Troops advanced so quickly that their requisitions fell behind and logistics and maintenance transactions slumped to nearly zero, leaving troops without supplies. Combat Service Support VSATs (CSS VSATs) were deemed to be the solution.

About 500 CSS VSATs now provide direct support to soldiers in Iraq and Afghanistan. The program has saved soldiers' lives in addition to time, marking a significant advance over the sneakernet, which required soldiers to go in harm’s way in convoys to hand-carry requisitions.

“Soldiers’ demand for CSS VSATs continues to increase because it allows users to share documents, pass requisitions, collaborate and conduct meetings online and make voice-over-IP telephone calls, all without moving from their location,” said Lt. Col. Tony Sanchez, product manager for Defense Wide Transmission Systems. The PM DWTS office is part of the Project Manager, Defense Communications and Army Transmission Systems of the Army’s Program Executive Office for Enterprise Information Systems.

Because logistics teams operate from fixed locations, size isn’t a driving factor. The size of satellite dishes has expanded, going from 3.1 feet to the current fourth-generation 3.9-foot Hawkeye II-Enhanced units.

That increase allows for greater beam coverage, which means less rain-fade degradation — the weakening of transmission caused by raindrops absorbing and scattering electromagnetic signals traveling through the atmosphere. To further enhance reliability and availability, these VSATs provide additional coverage zones and larger carriers with higher maximum data rates. Other changes include a redundant global infrastructure architecture, simplified cable-connector retrofit and additional cooling fans for modem chips.

Despite those augmentations, logistics teams have benefited from industry’s push to decrease size. The latest CSS VSAT model takes less effort to deliver.

“It fits into four transit cases, as opposed to five cases for the prototype model. It also weighs less, 519 pounds vs. 609 pounds for the prototype, a reduction of 90 pounds,” said Peter Nesby, assistant product manager at CSS SATCOM.

Light and easy

As logistics personnel ask developers to focus on reliability, more mobile forces continue to ask for equipment that’s smaller, lighter and simpler to deploy. Lightweight materials, advanced electronics and novel designs are contributing to the development of VSATs that warfighters can easily carry to remote sites and set up quickly.

GATR Technologies took an unusual path to trim weight and simplify antenna setup. A conducting composite fabric reflector is suspended in an inflatable sphere, using air pressure to push the reflector into shape. That eliminates the rigid reflector and the heavy metal support structure found in traditional antennas.

“The result is a 2.4-meter antenna that performs identical to a rigid 2.4-meter antenna but weighs 18 pounds and fits into an 80-liter bag,” said Larry Lowe, vice president of engineering at GATR. "A complete 2.4-meter GATR terminal fits into two airline checkable cases."

The company is also taking advantage of the rapid developments in consumer electronics. GATR is creating pointing assist applications that run on Android and iPhone devices.

“The smart phone will mount on the radome and the application will provide pointing feedback to the operator based on position sensors and signal levels in the modem," Lowe said.

TeleCommunication Systems has taken a different approach to slim down its Secure IP Router/Unclassified but Sensitive IP Router (SIPR/NIPR) Access Point (SNAP) terminals. Developed to provide secure beyond-line-of-sight communications to brigade and below, they’re designed for portability and ease of use.

“We reduced the size of the SNAP VSAT terminal through the replacement of the rigid 72-inch antenna feed boom, with one containing a hinge in the center, thus enabling it to fold and eliminating the need for an oversized case,” said Jim Sprungle, vice president of government programs at TCS.

To add versatility, the line employs modularity in the uplink and downlink radio-frequency signal chain. Operators can quickly change frequency bands, such as shifting from Ku band to Ka band, by simply disconnecting the feed boom and replacing it with a feed containing the other band’s equipment.

“Setup for a full 2-meter SNAP terminal takes 10 to 15 minutes to set up for mildly trained personnel," Sprungle said. "Setup time to change from one band to another takes five minutes or less.”

More power to you

Although a range of tactics brings improved reliability and smaller equipment, warfighters who require portable equipment still must deal with the weight of batteries. Advances in semiconductors move at roughly 100 percent every 18 months, but battery technology advances at less than 5 percent per year.

A military spokesman mused that without major changes in power sources, advances in semiconductors could possibly yield a VSAT the size of a wristwatch while battery packs would still weigh about 40 pounds. There’s some hope that alternative power sources could bring some assistance, such as using solar cells to extend battery lifetimes.

However, that seems as distant as a watch-sized VSAT. “Solar panels have had some success in charging smaller devices such as smart phones, but these developments have not yet matured enough to provide the power required by VSAT usage,” the DOD official said.

As batteries and alternative energy sources evolve, developers are pushing electronic technologies to trim power consumption. “The modem is the largest current draw in the system,” Lowe said. “Efficiencies in field programmable gate arrays and processor chips will directly influence the efficiency of future modem designs. AC-DC and DC-DC converters also reduce the power efficiency in the system.”

Although there’s clamor for more functionality, observers note that VSATs have dramatically changed warfare during the past few years.

“They give the warfighter the capability to provide a very large data pipe from the brigade all the way down to the farthest remote forward operating base level without having to field a trailer or large systems sitting on a Humvee," Sprungle said. "You do not need a vehicle; you just set SNAP up and you have communications.”